Primary air supplying means for an intake system of internal combustion engine

ABSTRACT

A primary air supplying means for an intake system of an internal combustion engine having a valve member adapted to permit the flow of a primary air during the deceleration of the engine, said valve member forming an orifice in cooperation with a valve housing for housing said valve member, and a sensing tube opened at the upstream of the orifice of the valve member when said valve member is in the open condition and opened at the downstream of a valve seat when said valve member is in the closed condition, the pressure present in said sensing tube being equalized to the negative pressure during the normal drive of the engine and to the atmospheric pressure during the deceleration thereof.

United States Patent [191 Tsumura et al.

[ PRIMARY AIR SUPPLYING MEANS FOR AN INTAKE SYSTEM OF INTERNAL COMBUSTION ENGINE [75] inventors: Terutoshi Tsumura, Aki-gun,

Hiroshima-ken; Koso Iida,

Hiroshima-shi, both of Japan [73] Assignee: Toyo Kogyo Co., Ltd.,

Hiroshima-ken, Japan 221 Filed: June 3, 1971 [21] Appl. No.: 149,543

[30] Foreign Application Priority Data June 4, 1970 Japan 45/55443 [52] US. Cl 123/97 B, 123/119 D, 123/117 A,

261/DIG. 19

[51] Int. Cl. F02d 31/00, F02b 33/00 [58] Field of Search 123/97 B, 119 D;

261/D1G 19,117 A [56] References Cited UNITED STATES PATENTS 3,287,899 l1/1966 Bintz 123/119 D l6 l7 I8 130 I0 1 I5 l3b 2| 22 23 [451 Aug. 14, 1973 Sarto 123/97 B Primary Examiner-Laurence M. Goodridge Assistant Examiner-Ronald B. Cox Attorney-Craig, Antonelli & Hill [57] ABSTRACT A primary air supplying means for an intake system of an internal combustion engine having a valve member adapted to permit the flow of a primary air during the deceleration of the engine, said valve member forming an orifice in cooperation with a valve housing for housing said valve member, and a sensing tube opened at the upstream of the orifice of the valve member when said valve member is in the open condition and opened at the downstream of a valve seat when said valve member is in the closed condition, the pressure present in said sensing tube being equalized to the negative pressure during the normal drive of the engine and to the atmospheric pressure during the deceleration thereof.

11 Claims, 3 Drawing Figures Pmmcowm mmsmwmmaaa aw m PIC-3.1

TERUTOSHI TSUMURA "a Rose mm- BY om pmwm 6 H411 ATTORNEYS FIG 2 PRIMARY AIR SUPPLYING MEANS FOR AN INTAKE SYSTEM OF INTERNAL COMBUSTION ENGINE The present invention relates to a primary air supplying means for an intake system of an internal combustion engine and, more particularly, to the primary air supplying means having a sensing tube, the pressure present in said sensing tube being, during the normal drive of an internal combustion engine, equalized substantially to the negative pressure present in an inlet passage and, during the deceleration of said engine, to the atmospheric pressure.

In an internal combustion engine heretofore largely employed in an automotive vehicle, it has been well known that, when the engine driving condition is shifted from the normal drive condition to the decelerated condition while a throttle valve in the carburetor disposed approximately amid the intake system is substantially closed, the value of pressure in the intake manifold connecting between the carburetor and the engine chamber is sharply reduced and a constant amount of air-fuel mixture is introduced into the engine chamber irrespective of the rotational number of the engine. It has also been known that, after the deceleration of the engine, the air-fuel mixture is usually enriched for a certain period of time with the addition of a small amount of the mixture supplied by an air stream under inertia, a fuel supplied during the idling and a small amount of residual fuel that has been wetted on the inner peripheral surface of the intake manifold. Specifically, the amount of fuel supplied to the engine chamber about the end of the deceleration is substantially equal to that of fuel supplied during the idling of the engine.

However, during the deceleration of the engine while the rotational number of the engine still remains relatively high, the amount of air-fuel mixture to be actually supplied into the engine chamber is nevertheless insufficient in relation to the optimum amount necessitated at this time. In addition, since the pressure in the intake manifold is sharply reduced as hereinbefore described, it has been often experienced that a considerable amount of exhaust gas created upon combustion of the air-fuel mixture in the engine chamber will flow back to the intake manifold particularly during a period in which the engine is shifted from the normal drive condition to the decelerated condition.

These disadvantages result in the frequent occurrence of misfire of the air-fuel mixture in view of the fact that the inflammability of the air-fuel mixture thus supplied during the deceleration of the engine is poor. If this misfire of the air-fuel mixture often occurs in a regular manner, the vehicle will run in the bumpy or surged running condition about the end of deceleration of the engine and/or the after-burning which accompanys an explosion will occur at the commencement of deceleration because an accumulated amount of unburned compounds of the exhaust gas present in the exhaust system is exploded under the influence of a subsequently incoming exhaust gas of high temperature.

The misfire of the air-fuel mixture also results in the emission of noxious unburned compounds of the exhaust gas to the atmosphere, which constitutes one of the most significant sources of atmospheric pollution in many cities of the world.

To eliminate these disadvantage, there has been proposed a primary air supplying device effective to supply a primary air to the inlet passage at the downstream of the throttle valve in the carburetor during the deceleration of the engine. However, in the internal combustion engine for use in an automotive vehicle, there are many elements to be controlled, such as the ignition timing, a secondary air to be supplied to the exhaust system, an ignition plug disposed in the reactor and so on,

Accordingly, an essential object of the present invention is to provide means for supplying the primary air to the inlet passage during the deceleration of the engine and concurrently detecting the deceleration of the engine.

Another object of the present invention is to provide a primary air supplying means having a sensing tube capable of introducing the inlet vacuum during the normal drive of the engine and introducing the atmospheric pressure during the deceleration of the engine for the purpose of detecting the deceleration of the en gine.

A further object of the present invention is to provide a primary air supplying means for an intake system of an internal combustion engine, said sensing tube being capable of controlling a mechanism to be operated during the deceleration of the engine.

A still further object of the present invention is to provide the primary air supplying means by which a great amount of the primary air can be continuously supplied to effect a complete misfire thereby to prevent the after-burning and surging phenomenon with substantial reduction of the amount of unburned compounds present in the exhaustgas.

A still further object of the present invention is to provide a primary air supplying means having a sensing tube capable of, during the deceleration of the engine, controlling the ignition system of the engine or the ignition device disposed in the reactor so that the amount of unburned compounds present in the exhaust gas can be advantageously reduced.

These and other objects and features of the present invention will become apparent from the following description taken by way of example in conjunction with preferred embodiments thereof with reference to the accompanying drawings, in which;

FIG. l is a longitudinal sectional view of a primary air supplying means in one embodiment of the present invention,

FIG. 2 is a longitudinal sectional view of a portion of said primary air supplying means in another embodiment of the present invention, and

FIG. 3 is a similar view to FIG. 2, showing a further embodiment of the present invention.

Referring now to FIG. 1, the primary air supplying means according to the present invention is generally indicated by 10 and rigidly secured to a wall portion 11 of an intake manifold 12 at the downstream of a throttle valve (not shown) provided in the carburetor (also not shown).

This primary air supplying means 10 includes a valve housing 13 having radially outwardly extending flanges 13a and 13b at its both ends and formed at a substantially intermediate portion with an opening 14 connected with an air source, for example, an air cleaner (not shown), through a conduit 15. This valve housing 13 is at one end adjacent to the flange 13a closed airtightly by a plug 16 with a disphragm member 17 nondetachably interposed between said plug 16 and said flange 13a, forming a diaphragm chamber 18 as defined between the plug 16 and the diaphragm member 17. This plug 16 is provided, as shown, with a hole 19 through which a hollow member 20 is extended as will be mentioned later.

Situated substantially between the valve housing 13 and the wall portion 11 of the intake manifold 12 is a cylindrical block 21 having a longitudinally extending cavity 22 and integrally formed at an intermediate portion with a radially outwardly extending collar 23 airtightly sandwiched between the flange 13b of the valve housing 13 and the wall portion 11 of the intake manifold 12. This cylindrical block 21 also has one end situated within the valve housing 13 and integrally formed with a bushing 24 for slidably supporting a piston assembly 25 therethrough and the other end situated within a recess 26 formed in the wall portion 11, said recess 26 being communicated with the intake manifold 12 through a bore 27.

As shown, the end of the cylindrical block 21 situated within the valve housing 13 is formed at its lateral side with a cut-out portion 28 to establish the com munica tion between the interior of the valve housing 13 and the cavity 22 while the other end situated within the recess 26 is stepped at 29 to form a reduced end portion 30 having a valve seat 31.

The cylindrical block 21 is also formed therein with a passage 32 having one open end 32a open to a spacing definedlby the lateral side surface of the recess 26 and the reduced end portion 30 of the cylindrical block 21 and the other open end 32b connected with a hollow member 33 rigidly secured to that portion of the-collar 23, which is in turn connectedwith the hollow member 20 in any known manner, for example, by means of couplings 34, 35 and 36 as shown by which a sensing tube can be thus formed. However, for the sake of brevity, the passage 32 shown as extending from the reduced end portion30 to that portion of the collar 23 in the cylindrical block 21 is construed as the sensing tube adapted to communicate the open end 32a directly to the diaphragm chamber 18. For example, if the valve housing 13 has a wall of sufficient thickness, this passage 32 may be disposed via the wall of the valve housing 13 without necessitating any couplings such as indicated by 20, 33, 34, 35 and 36.

For the purpose as will be mentioned later, the re duced end portion 30 is provided at its valve seat 31 with an aperture 31a communicated with said sensing tube.

The piston assembly 25 extending in the longitudinal direction within the valve housing 13 and the cavity 22 while slidably supported by the bushing 24 integral with the cylindrical block 21 has one end connected with a portion of the diaphragm member 17 by means of a suitable fastening member such as shown by 37 and the other end rigidly connected with a valve member 38 having an elastic mat 39, preferably made of synthetic rubber material, of about the same size as that of said valve seat 31. This piston assembly 25 is movable between a first position in which, as shown, the cavity 22 is closed by the valve member 38 and a second position in which the cavity 22 is communicated with the recess 26 as will be mentioned later, said piston assembly 25 being normally urged to the first position by a coil spring 40 which is interposed between the diaphragm member 17 and that end of the cylindrical block 21 around the bushing 24.

The valve member 38 should be so sized that, when the piston assembly'25 is shifted from the first position to the second position against the spring 40 under the influence of the negative pressure present in the intake manifold 12, air supplied from the air source to the cavity 22 through the opening 14 and then the cutout portion 28 by means of the conduit 15 can flow into the intake manifold 12 through a clearance 41 which is formed between the lateral side of said valve member 38 and the lateral surface of the recess 26 and acts as an orifice. The amount of the primary air to be supplied to the intake manifold 12 can be dependent upon the size of the clearance or orifice 41. However, this clearance or orifice 41 should be so sized that a large amount of the primary air can be supplied to the intake manifold and thus the engine chamber to effect a complete misfire of the air-fuel mixture in the engine chamber. Despite that the misfire occurs in the engine chamber, the diluted mixture can be properly enriched in a reactor (not shown) disposed in the exhaust system to an extent that the unfired mixture is completely combusted in the reactor. I I r p I The elastic mat 39 secured to the end of the piston assembly 25 together with the valve member 38 is provided to ensure the tight closure of the cavity 22 when the piston assembly 25 is in the first position and also to absorb, if any, a shock which will possibly occur upon abutment of the valve member 38 to the valve seat 31. However, this elastic mat 39 has no significance if the tight closure of the cavity 22-by the-valve memeber 38 is ensured in any way.

The open end 32a of the passage 32 formed in the reduced end portion 30 as hereinbefore described should be arranged such that, when the piston assembly 25 is in the second position, a portion of the air flowing from the cavity 22 into the recess 26 through the orifice 41 under the influence of the negative pressure present in the manifold 12 can be sucked into the diaphragm chamber 18 through the passage 32. This can be achieved because, despite that the air to be supplied into the intake manifold 12 from the cavity 22 via the recess 26 flowsiat a high speed, a suction force can be created in the diaphragm chamber 18 and thus the passage 32 as the piston assembly 25 is shifted from the first position to the second position against the spring 40. Introduction of the air through the passage 32 into the diaphragm chamber 18 ensures the maintenance of the piston assembly 25 in the second position during a period in which the value of pressure in the intake manifold 12 is smaller than the value of pressure in the cavity 22 or the atmospheric pressure, since the value of pressure in the diaphragm 18 that had been considerably reduced at the moment the piston assembly 25 was shifted to the second position is equalized'to that in the cavity 22 or the atmospheric pressure by the instrocluction of the air into the diaphragm chamber 18. However, the aperture 31a formed at the valve seat 31 and adapted to be closed by the valve member 38 when the piston assembly 25 is in the first position is so provided as hereinbefore described that equalization of the pressure in the diaphragm chamber 18 to the pressure in the cavity 22 or the atmospheric pressure can be more readily achieved than in the case where this aperture 310 is omitted.

In the instance as shown in FIG. 2, the end of the cylindrical block 21 situated within the recess 26 is inclined from a substantially intermediate portion thereof toward the valve seat 31 while the open end 320 of the passage 32 is formed at the inclined surface 30.

Alternatively, the passage 32 which has been described as formed in the cylindrical block 21 in the first and second embodiments of the present invention with reference to FIGS. 1 and 2 may be formed in the wall portion of the intake manifold 12, as shown in FIG. 3, with the open end 32a thereof open to a spacing defined by the inclined surface 30 and the valve member 38 seated to the valve seat 31 through the elastic mat 39 sandwiched therebetween. If this spacing is not provided, the passage 32 may be opened in the recess 26 at the upstream of the orifice 41 of the valve member 38 which is in open position. The other open end 320 of said passage 32 is connected with a suitable detecting means for detecting the driving condition of the engine, without utilizing the diaphragm chamber 18. In addition, in the instance shown in FIG. 3, instead of the piston assembly 25 shown in FIGS. 1 and 2 which has been omitted in FIG. 3, a compression spring 42 is provided between the depth of the recess 26 and the adjacent surface of the valve member 38 which is slidably received in said recess 26. The orifice 41 is formed in the valve member 38 at any position outside the surface thereof occupied by the cross-sectional area of the valve seat 31.

Particularly in the instance shown in FIG. 3, the open end 32a of the passage 32 may be formed at any position in the wall portion 11 if this open end 32a is situated in register with the thickness of the valve member 38 or at the upstream of the orifice 41 when the valve member 38 is in position to permit the flow of air from the cavity 22 to the recess 26. It is, however, to be noted that, in the both instances shown in FIGS. 2 and 3, the aperture 31a communicated with the passage 32 in FIG. 1 is omitted. Nevertheless, the arrangements shown in FIGS. 2 and 3 function to achieve the substantially same objects as can be obtainable by the arrangement shown in FIG. 1.

Before the operation of the primary air supplying means thus constructed in accordance with the present invention, it is to be noted that a passage connecting between the interior of the valve housing 13 to the intake manifold 12 through the cavity 22 and the recess 26 is construed as a primary air passage.

In operation, assuming that the internal combustion engine equiped with the primary air supplying means of the present invention and mounted in an automotive vehicle is driven in the normal drive condition, the valve member 38 is abutted against the valve seat 31 by the action of the spring 40 so that the negative pressure in the intake manifold 12 can be introduced into the sensing tube. Accordingly, this negative pressure can be supplied to the diaphragm chamber 18 through said sensing tube whereby the valve member 38 can be upwardly moved by the piston assembly 25 connected with the diaphragm member 17 of the diaphragm chamber 18 so that the valve member 38 can be rigidly abutted against the valve seat 31.

However, during the deceleration of the engine established upon substantial closure of the throttle valve, the negative pressure in the intake manifold will be sharply increased. For this reason, the valve member 38 can be downwardly moved against the both intrinsic resiliences of the spring 40 and the diaphragm member 17. Therefore, the primary air can be supp-lied from the air cleaner to the upstream of the valve member 38 through the conduit 15 and then the primary air passage and further supplied therefrom to the intake manifold 12 through the orifice 41 formed between the lat eral side of the valve member 38 and the inner surface of the recess 26. Because of the provision of this orifice 41, differential pressure can be created between the upstream and downstream of the valve member 38. In other words, the pressure present at the upstream of the orifice 4B is substantially equal to the atmospheric pressure while the pressure present at the downstream thereof is substantially equal to the negative pressure in the intake manifold 12. Accordingly, the sensing tube opened to the upstream with respect to the orifice 41 can introduce the atmospheric pressure into the diaphragm chamber 18 thereby to steadily maintain the valve member 38 in the open position against the action of the spring 40.v

The aperture 31a is adapted to introduce the atmospheric pressure into the intake manifold immediately upon opening of the valve member 38 so that the responsibility can be favourably improved.

When the engine is subsequently shifted from the decelerated condition to the normal drive condition, the valve member 38 can be seated against the valve seat 31 by the action of the spring 40 since the pressure in the intake manifold 12 is increased. Thus, the primary air passage can be closed. Thereaftenthe operation can be returned back to the normal drive condition.

Although the present invention has been fully disclosed by way of example in the form of the preferred embodiments thereof, various modification and change are apparent to those skilled in the art. For example, the primary air supplying means may be set to enable a proper amount of the primary air to be supplied to the intake manifold to achieve the complete combustion in the combustion chamber of the engine at the proper time and the ignition device of the engine can be controlled by the sensing tube to prevent the after-burning and concurrently to reduce the amount of unburned compounds present in the exhaust gas. Furthermore, the primary air supplying means of the present invention can be utilized to enable the sensing tube to control the operation of the ignition device disposed in the reactor thereby to remove the unburned compounds present in the exhaust gas.

Thus, the primary air supplying means having the sensing tube in accordance with the present invention may be utilized in such a manner that said sensing tube is connected with means which is to be controlled depending upon the deceleration or normal drive, to achieve objects of said means.

In FIG. 1 A Control Device is schematically shown connected to the sensing tube 32 by way of line 36'. This line 36' is shown in dash lines to illustrate the optional arrangement of such A Control Device, with or without the specific connection of the tube 32 to the diaphragm valve control for the primary air valve.

What is claimed is:

II. An air supplying arrangement for an air intake system of an internal combustion engine; said arrangement comprising:

and air source for supplying primary air,

an inlet passage arranged downstream of an engine throttle valve for supplying air and fuel to combustion chambers of the engine,

a primary air passage extending between said air soucc and said inlet passage,

primary air valve means arranged in said primary air passage adjacent said inlet passage and including 7 means for opening said primary air passage to said inlet passage in response to engine deceleration conditions and including means for closing said primary air passage with respect to said inlet passage in response to operation of the engine under other than deceleration conditions, a sensing tube, means for directly communicating said sensing tube with the pressure in said primary air passage at a position upstream of said primary air valve means when said primary air valve means is open,

means for directly communicating said sensing tube with the pressure in the inlet passage when said primary air valve means is closed, and

control device means operatively connected to said sensing tube for controlling operating parameters of the engine in direct response to the pressure existing in the sensing tube.

2. An arrangement according to claim 1, wherein said means for directly communicating said sensing tube with the pressure in the inlet passage includes an orifice arranged in one of a valve member of said primary air valve means and a wall of said primary air passage adjacent said valve member, said orifice being dimensioned such that, when the primary air valve means is open, a pressure differential exists at opposite sides of the orifice with the side of the orifice communicating with the sensing tube being at the pressure in said primary air passage and with the side of the orifice communicating with the inlet passage being at the pressure in said inlet passage, whereby said sensing tube experiences the pressure in said primary air passage substantially unaffected by the pressure in said inlet passage when said primary air valve means is open.

3. An arrangement according to claim 2, wherein said means for opening said primary air passage includes the dimensioning of said valve member such that increased negative pressure in said inlet passage during deceleration conditions effects the movement of said valve member to the open position.

4. An arrangement according to claim 3, wherein said means for closing said primary air passage includes resilient means continually pushing said valve member toward the closed position.

5. An arrangement according to claim 2, wherein said valve member is surrounded by a chamber leading from and arranged above the intake passage, said orifice being positioned between an outer edge of the valve member and wall portions of said chamber, said sensing tube being open to said chamber at a position above said orifice.

6. An arrangement accord rig to claim 2, wherein a valve seat for said valve member includes an inclined surface which forms a wall of said chamber, said sensing tube being opened at said inclined surface.

7. An arrangement according to claim 2, wherein said orifice extends through a part of said valve member.

8. An arrangement according to claim 2, wherein a valve seat for said valve member is provided with an aperture communicating with the sensing tube, which aperture is open to said primary air passage when said primary air valve means is open and is closed to said primary air passage when said primary air valve means is closed. V

9. An arrangement according to claim 4, wherein said control device means includes primary air valve assisting means for assisting in closing and opening said primary air valve means.

10. An arrangement according to claim 9, wherein said primary air valve assisting means comprises a diaphragm device including a diaphragm and a diaphragm chamber, said diaphragm being rigidly connected with said valve member and said diaphragm chamber being communicated with said sensing tube whereby said valve member can maintain the primary air passage in the closed condition by the resilient means and the negative pressure introduced from said inlet passage through said sensing tube to said diaphragm chamber during the normal drive of the engine and can maintain the primary air passage in the open condition by the negative pressure acting on the valve member and the primary air pressure introduced from said primary air passage through said sensing tube to said diaphragm chamber during the deceleration of the engine.

11. An arrangement according to claim 10, wherein said control device means includes additional means for controlling operating parameters of the engine other than the flow of primary air. 8 i i WTED STATES PATENT @FFICE @ERHHCATE @F CGRHECTION Patent No. 3, 752 131 Dateci Aug 14, 1973 Inventofls) Terutoshi Tsumura and Koso Iida It is certified that error appears in the above-identified patent and that said Letters Patent are hereby porzrectec? as shown below:

Portion of Figure 1 which now appears asz should appear as follows:

DE VICE Signed and sealed this 30th day of April 1971;.

(SEAL) Attest:

ED E'IAIED I'LFLETCHEP JRQ o MARSHALL DANN Attesting Officer Commissioner of Patents 

1. An air supplying arrangement for an air intake system of an internal combustion engine; said arrangement comprising: and air source for supplying primary air, an inlet passage arranged downstream of an engine throttle valve for supplying air and fuel to combustion chambers of the engine, a primary air passage extending between said air souce and said inlet passage, primary air valve means arranged in said primary air passage adjacent said inlet passage and including means for opening said primary air passage to said inlet passage in response to engine deceleration conditions and including means for closing said primary air passage with respect to said inlet passage in response to operation of the engine under other than deceleration conditions, a sensing tube, means for directly communicating said sensing tube with the pressure in said primary air passage at a position upstream of said primary air valve means when said primary air valve means is open, means for directly communicating said sensing tube with the pressure in the inlet passage when said primary air valve means is closed, and control device means operatively connected to said sensing tube for controlling operating parameters of the engine in direct response to the pressure existing in the sensing tube.
 2. An arrangement according to claim 1, wherein said means for directly communicating said sensing tube with the pressure in the inlet passage includes an orifice arranged in one of a valve member of said primary air valve means and a wall of said primary air passage adjacent said valve member, said orifice being dimensioned such that, when the primary air valve means is open, a pressure differential exists at opposite sides of the orifice with the side of the orifice communicating with the sensing tube being at the pressure in said primary air passage and with the side of the orifice communicating with the inlet passage being at the pressure in said inlet passage, whereby said sensing tube experiences the pressure in said primary air passage substantially unaffected by the pressure in said inlet passage when said primary air valve means is open.
 3. An arrangement according to claim 2, wherein said means for opening said primary air passage includes the dimensioning of said valve member such that increased negative pressure in said inlet passage during Deceleration conditions effects the movement of said valve member to the open position.
 4. An arrangement according to claim 3, wherein said means for closing said primary air passage includes resilient means continually pushing said valve member toward the closed position.
 5. An arrangement according to claim 2, wherein said valve member is surrounded by a chamber leading from and arranged above the intake passage, said orifice being positioned between an outer edge of the valve member and wall portions of said chamber, said sensing tube being open to said chamber at a position above said orifice.
 6. An arrangement accord ng to claim 2, wherein a valve seat for said valve member includes an inclined surface which forms a wall of said chamber, said sensing tube being opened at said inclined surface.
 7. An arrangement according to claim 2, wherein said orifice extends through a part of said valve member.
 8. An arrangement according to claim 2, wherein a valve seat for said valve member is provided with an aperture communicating with the sensing tube, which aperture is open to said primary air passage when said primary air valve means is open and is closed to said primary air passage when said primary air valve means is closed.
 9. An arrangement according to claim 4, wherein said control device means includes primary air valve assisting means for assisting in closing and opening said primary air valve means.
 10. An arrangement according to claim 9, wherein said primary air valve assisting means comprises a diaphragm device including a diaphragm and a diaphragm chamber, said diaphragm being rigidly connected with said valve member and said diaphragm chamber being communicated with said sensing tube whereby said valve member can maintain the primary air passage in the closed condition by the resilient means and the negative pressure introduced from said inlet passage through said sensing tube to said diaphragm chamber during the normal drive of the engine and can maintain the primary air passage in the open condition by the negative pressure acting on the valve member and the primary air pressure introduced from said primary air passage through said sensing tube to said diaphragm chamber during the deceleration of the engine.
 11. An arrangement according to claim 10, wherein said control device means includes additional means for controlling operating parameters of the engine other than the flow of primary air. 